The semiconductor integrated circuit industry has experienced rapid growth in the past several decades. Technological advances in semiconductor materials and design have produced increasingly smaller and more complex circuits. These material and design advances have been made possible as the technologies related to processing and manufacturing have also undergone technical advances. In the course of semiconductor evolution, the number of interconnected devices per unit of area has increased as the size of the smallest component that can be reliably created has decreased.
One commonly used technique employed to form material layers over semiconductor wafers is physical vapor deposition, which includes the technique of sputtering. In sputtering deposition, a plasma is used to excite ions, typically of a noble gas, to facilitate forceful collisions with a target. Atoms of the target are knocked free by the colliding ions and then condense on the exposed surface of a semiconductor wafer forming a thin layer or film of the target material. Some other PVD chambers may also be used in an etching process by exciting ions, noble gases or metal ions, and generating collisions with the layer to be etched on the semiconductor wafer. As the feature size has decreased, providing sputtered material layers with even coverage on the features on a semiconductor wafer has become increasingly difficult.
Aspects of the present disclosure may be best understood by viewing the accompanying figures with reference to the detailed description provided below.